Differences between prokaryotic and eukaryotic cell | Cell Membrane and Cytoplasm 

Prokaryotic cell

• Cell is usually small.
• Cell wall if present possesses muramic acid.
• DNA is usually circular and naked , i.e. , without an association .
• An organised nucleus is absent , instead a nucleoid is found .

• Cell organelles like ER , mitochondria , Golgi apparatus , lysosomes , centrioles , etc. , are absent .
• Ribosomes are of 70S type .
• The amount of DNA remains the same as haploid and diploid stages are absent .
• Transcription and translation occur in the cytoplasm .

Eukaryotic cell

• Cell is comparatively larger
• An organised nucleus is found that is differentiated into nuclear envelope , chromatin , one or more nucleoli and nucleoplasm.
• Cell wall if present , is without muramic acid . Animal cells lack cell wall while those of plants and fungi possess cell wall.

• Nuclear DNA is linear and associated with histone proteins . Extra nuclear DNA is present in chloroplast and mitochondria .
• The amount of DNA shows a regular alternation between diploid and haploid stages.
• Transcription occurs in the nucleus while translation occurs in cytoplasm .
• ER , mitochondria , Golgi apparatus or their equivalents are present in all the eukaryotic cells . Centrioles are usually present in animal cells .
• Ribosomes are of 805 type .

Cell Membrane

• Cell membrane or plasma membrane is quasifluid , elastic , pliable , film - like covering which surrounds the cytoplasm and also covers the cell organelles inside the cytoplasm
• It is semipermeable for water and selectively permeable for solutes and is made up of phospholipid bilayer.

Structure

• The fluid mosaic model is most accepted structural model of cell membrane . It was proposed by Singer and Nicolson in 1972. According to this model , there is a bilayer of lipid molecules ( phospholipid ) with globular protein molecules of two types integral or transmembrane protein and peripheral or extrinsic protein and sterols which are arranged in different manner in different regions of the plasma membrane.

Functions

• It causes compartmentalisation and allows organelles to maintain identity .
• Selective permeability of plasma membrane enables it to control the exchange between cell and its environment . Other specialised functions are absorption , secretion , fluid transport , electric coupling and other physiological processes.

Cytoplasm and Cytoplasmic Matrix

Structure

• The jelly - like , semi - fluid general mass of protoplasm excluding nucleus is cytoplasm that includes cytoplasmic matrix and cell organelles.
• Cytoplasmic matrix is crystallo - colloidal complex in water which constitutes about 90 % of matrix and other colloidal solution such as minerals , sugars , amino acids , etc.

Functions

• Matrix is the site of synthesis of a number of biochemicals like fats , nucleotides , carbohydrates , proteins , etc.
• Many important pathways such as glycolysis , pentose phosphate pathway and anaerobic respiration occur the cytoplasmic matrix .

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